XML 103 R102.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Employee Benefit Plans (Details)
1 Months Ended 12 Months Ended
Feb. 08, 2018
Feb. 28, 2018
Dec. 31, 2019
USD ($)
$ / shares
shares
Dec. 31, 2018
USD ($)
shares
Dec. 31, 2017
USD ($)
shares
Share-based Payment Arrangement [Abstract]          
Employer matching contribution, percent of match for first 3% of compensation     100.00%    
Employer matching contribution, percent of employees' gross pay, first 3%     3.00%    
Employer matching contribution, percent of match for the next 2% of compensation     50.00%    
Employer matching contribution, percent of employees' gross pay, next 2%     2.00%    
Employer matching contribution, percent of match total     4.00%    
Employer matching contribution, percent of employees' gross pay total     5.00%    
Employee stock ownership plan, contribution expense     $ 13,021,000 $ 10,769,000 $ 6,343,000
Deferred compensation expense     $ 2,294,000 2,309,000 1,596,000
Defined Contribution Plan Disclosure [Line Items]          
Purchase price of common stock (as percent)     95.00%    
Stock split, conversion ratio 2 2      
Allocated stock-based compensation expense     $ 12,921,000 $ 11,227,000 $ 11,763,000
Compensation not yet recognized, stock options     0    
Compensation not yet recognized, share-based awards other than options     $ 20,852,000    
Compensation cost not yet recognized, period for recognition     1 year 10 months 24 days    
Options outstanding, intrinsic value     $ 2,993,000    
Options exercisable, intrinsic value     $ 2,993,000    
Share price (in dollars per share) | $ / shares     $ 26.79    
Options, exercises in period | shares     3,050 111,728 122,012
Options, exercises in period, intrinsic value     $ 43,000 $ 561,000 $ 1,329,000
Options, grants in period, gross | shares     0 0 0
Employee Stock Purchase Plan 2015          
Defined Contribution Plan Disclosure [Line Items]          
Maximum annual contributions per employee, amount     $ 25,000    
Service period     6 months    
Special Employee Stock Purchase Plan 2015          
Defined Contribution Plan Disclosure [Line Items]          
Maximum annual contributions per employee, amount     $ 10,000    
Purchase price of common stock (as percent)     85.00%